As if cancer, an epidemic of childhood asthma and heart disease weren't enough reasons to take precautionary action regarding pollution of the air water and soil, global chemical contamination now threatens the talent and intelligence of future generations.

Concern is growing worldwide over the long-term health effects of chemicals known as persistent organic pollutants (POPs). Exposure to POPs is shifting the IQ of the population downward ”“ more developmentally-challenged people and fewer gifted people, according to Lynn Goldman, MD, MPH, Johns Hopkins University pediatrician and epidemiologist.

These pollutants are toxic and they don't go away. Instead of degrading, they accumulate and remain in the tissue of humans and animals and other ecosystems for a long period. This bio-accumulation of toxic chemicals increases the risk for diseases such as cancer. It also contributes to abnormalities in brain development and in the reproductive systems of animals and human beings.

The U.S. Government continues to allow the petrochemical industry and power plants to emit toxic substances without accurate monitoring and without a national plan for reducing or cleaning up toxic waste. When DDT, one of the pesticides classified as a POP, was banned in the United States, the government shipped remaining supplies to developing countries. The lack of precaution in this "goodwill" gesture is now coming back to haunt this country. It is now known that contamination of the environment with persistent organic pollutants is not contained within a country's boundaries. POPs are often transported long distances via air, water and migratory species.

Global efforts to eliminate POPs have been developing since the early 1990s. The Stockholm Convention on Persistent Organic Pollutants, signed by several nations including the United States in May 2001, calls for the elimination of 12 POPs, including the pesticides aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex and toxaphene, as well as PCBs. It also calls for restricting use of DDT to disease vector control until safe, affordable and effective alternatives are in place; mandating removal of PCB equipment; and encouraging minimization of unintentional release of dioxins and furans. The treaty has a provision for adding other POPs to the elimination list and for preventing the introduction of new POPs into commerce. It also calls for providing technical and financial assistance to developing countries and countries with economies in transition.

The list of serious health effects from exposure to POPs is very long: POPs can cause endocrine disruption ”“ changes in hormones that can affect brain development and the reproductive system. DDT and DDE are examples of two pesticides now banned in the United States but still persists in the environment and used in other countries. One study showed that birds exposed to these pesticides became infertile because the hormone for maturation of eggs was blocked. Another study of mothers exposed to DDT found that they had a shorter lactation period. Mothers that were not exposed to DDT were able to breast feed their babies seven-and-a-half months while mothers exposed to DDT had a lactation period of only three months. Still other studies have found that women exposed to DDE have preterm births.

Exposure to POPs, such as DDT and DDE may cause fertility problems in future generations. One study found that for every 10 milligrams per liter of DDT exposure in the mother, the daughter's pregnancy probability dropped 32 percent.

Exposure to polychlorinated byphenols (PCBs), another POP, can cause developmental delays. A decrease in birth weight and motor development delay in newborns have been linked to mothers' PCB exposure. Other studies show defects in visual recognition memory and delays in cognitive development related to PCB exposure.

The replacement now being used for PCBs, polybrominated diphenyl ether (PBDEs), is no safer than PCBs. Studies show this chemical is similar to PCBs in the brains of animals, and is as harmful to the environment.

Citizens, especially health care professionals who are seeing the health effects of exposure to POPs, must urge the State and U.S. Governments to develop and implement a plan for eliminating POPs from the environment.

Australia has set an example for other countries to follow by establishing a National Advisory Body to gather general community and industry support. The national plans for management of toxic waste developed by the group over a three year period were accepted by State and Federal Government. Such a conscious, intelligent process for eliminating hazardous toxins from the environment is overdue in the United States. Solutions are needed now.

For more information on the on the Stockholm Convention on Persistent Organic Pollutants (POPs), and a listing and description of POPs, go to www.oztoxics.org.

Vicki Wolf is an environmental and health writer. She also is a consultant on website content and design, and leadership communications. Vicki lives in Austin, Texas where she teaches yoga, and studies Spanish and guitar. More of her writing can be found at www.cleanhouston.org.